validate <-
  function(fit,  method="boot", B=40,
           bw=FALSE, rule="aic", type="residual", sls=0.05, aics=0, 
           force=NULL, estimates=TRUE, pr=FALSE,...)
  UseMethod("validate")


#Resampling optimism of discrimination and reliability of an ols regression
#B: # reps
#bw=T to incorporate backward stepdown (using fastbw) with params rule,type,sls
#pr=T to print results of each bootstrap rep
#Requires: predab.resample, fastbw, ols
#Frank Harrell 11 June 91

validate.ols <- function(fit, method="boot",
	 B=40, bw=FALSE, rule="aic", type="residual",
	 sls=.05, aics=0, force=NULL, estimates=TRUE,
    pr=FALSE, u=NULL, rel=">", tolerance=1e-7, ...)
{
  fit.orig <- fit
  
  penalty.matrix <- fit.orig$penalty.matrix
  
  discrim <- function(x, y, fit, iter, evalfit=FALSE, u=NULL, rel=NULL,
                      pr=FALSE, ...)
	{
      resid <- if(evalfit) fit$residuals else y - x

      n <- length(resid)
      sst <- (n - 1) * var(y)   # sum(y^2) - (sum(y)^2)/n
      mse <- sum(resid^2)
      rsquare <- 1 - mse / sst
      mse <- mse / n

      if(evalfit) {	#Fit being examined on sample used to fit
        intercept <- 0
        slope     <- 1
      } else {
        if(length(fit$coef)==1) {intercept <- mean(y)-mean(x); slope <- 1}
        else {
          coef <- lsfit(x, y)$coef   #Note x is really x*beta from other fit
          intercept <- coef[1]
          slope     <- coef[2]
        }
      }
      
      z <- c(rsquare, mse, GiniMd(slope*x), intercept, slope)
      nam <- c("R-square", "MSE", "g", "Intercept", "Slope")
      if(length(u)) {
        yy <- if(rel==">") ifelse(y>u,  1, 0)
        else if(rel==">=") ifelse(y>=u, 1, 0)
        else if(rel=="<")  ifelse(y<u,  1, 0)
        else ifelse(y <= u, 1, 0)
        z <- c(z, somers2(x,yy)["Dxy"])
        nam <- c(nam, paste("Dxy Y", rel, format(u), sep=""))
        if(rel==">"|rel==">=") P <- pnorm(- (u - x) / sqrt(mse))
        else P <- pnorm((u - x) / sqrt(mse))
        P0 <- sum(yy) / n
        L <- -2*sum(yy * logb(P)  + (1 - yy) * logb(1 - P ))
        L0<- -2*sum(yy * logb(P0) + (1 - yy) * logb(1 - P0))
        R2 <- (1 - exp(-(L0 - L) / n)) / (1 - exp(-L0 / n))
        z <- c(z, R2)
        nam <- c(nam, paste("R2 Y", rel, format(u), sep=""))
      }
      names(z) <- nam
      z
    }
  
  ols.fit <- function(x, y, tolerance=1e-7, backward, 
                      penalty.matrix=NULL, xcol=NULL, ...)
  {
    fail <- FALSE
    if(!length(x)) {
      ybar <- mean(y)
      n <- length(y)
      residuals <- y - ybar
      v <- sum(residuals ^ 2) / (n - 1)
      return(list(coef=ybar, var=v / n, residuals=residuals, fail=fail))
    }
    if(length(penalty.matrix) > 0) {
      if(length(xcol)) {
        xcol <- xcol[-1] - 1   # remove position for intercept
        penalty.matrix <- penalty.matrix[xcol, xcol, drop=FALSE]
      }
      fit <- lm.pfit(x, y, penalty.matrix=penalty.matrix,
                     tol=tolerance)
      if(any(is.na(fit$coefficients))) fail <- TRUE
    }
    else {
      fit <- lm.fit.qr.bare(x, as.vector(y), tolerance=tolerance,
                            intercept=TRUE, xpxi=TRUE)
      if(any(is.na(fit$coefficients))) fail <- TRUE
      if(backward) 
        fit$var <- sum(fit$residuals^2) * fit$xpxi/
          (length(y) - length(fit$coefficients))
    }
    c(fit, fail=fail)
  }
  
  predab.resample(fit.orig, method=method, fit=ols.fit, measure=discrim,
                  pr=pr, B=B, bw=bw, rule=rule, type=type, sls=sls, aics=aics,
                  force=force, estimates=estimates, tolerance=tolerance,
                  backward=bw,u=u, penalty.matrix=penalty.matrix,
                  rel=rel, ...)
}

print.validate <- function(x, digits=4, B=Inf, ...)
{

  if(prType() == 'html')
    return(html.validate(x, digits=digits, B=B, ...))
  
    kept <- attr(x, 'kept'); attr(x, 'kept') <- NULL
    print(round(unclass(x), digits), ...)
    if(length(kept) && B > 0) {
      cat("\nFactors Retained in Backwards Elimination\n\n")
      varin <- ifelse(kept, '*', ' ')
      print(varin[1:min(nrow(varin), B),], quote=FALSE)
      cat("\nFrequencies of Numbers of Factors Retained\n\n")
      nkept <- apply(kept, 1, sum)
      tkept <- table(nkept)
      names(dimnames(tkept)) <- NULL
      print(tkept)
    }
  }

latex.validate <- function(object, digits=4, B=Inf, file='', append=FALSE,
                           title=first.word(deparse(substitute(x))),
                           caption=NULL, table.env=FALSE,
                           size='normalsize',
                           extracolsize=size, ...)
  {
    chg <- function(x, old, new) {
      names(new) <- old
      tx <- new[x]
      ifelse(is.na(tx), x, tx)
    }
    x <- object
    kept <- attr(x, 'kept'); attr(x, 'kept') <- NULL
    cn <- colnames(x)
    cn <- chg(cn, c('index.orig', 'training', 'test', 'optimism',
                    'index.corrected', 'n'),
              c('Original\nSample', 'Training\nSample',
                'Test\nSample', 'Optimism', 'Corrected\nIndex',
                'Successful\nResamples'))
    rn <- rownames(x)
    rn <- chg(rn, c('Dxy','R2','R-square','Emax','D','U','Q','B','g','gp','gr','rho','pdm'),
              c('$D_{xy}$','$R^{2}$','$R^{2}$', '$E_{\\max}$','$D$','$U$',
                '$Q$','$B$','$g$','$g_{p}$','$g_{r}$','$\\rho$',
                '$|\\overline{\\mathrm{Pr}(Y\\geq Y_{0.5})-\\frac{1}{2}}|$'))
    dimnames(x) <- list(rn, cn)
    cat('\\Needspace{2in}\n', file=file, append=append)
    cat('\\begin{center}\\', size, '\n', sep='', file=file, append=append)
    if(length(caption) && !table.env)
      cat(caption, '\n\n', sep='', file=file, append=TRUE)
    cdec <- ifelse(cn == 'Successful\nResamples', 0, digits)
    latex(unclass(x), cdec=cdec, rowlabel='Index',
          title=title, caption=if(table.env) caption,
          table.env=table.env, file=file, append=TRUE,
          center='none', extracolsize=extracolsize, ...)
    cat('\\end{center}\n', file=file, append=TRUE)

    if(length(kept) && B > 0) {
      varin <- ifelse(kept, '$\\bullet$', ' ')
      nr <- nrow(varin)
      varin <- varin[1:min(nrow(varin), B),, drop=FALSE]
      cat('\\Needspace{2in}\n', sep='',
          file=file, append=append)
      cat('\\begin{center}\\', size, '\n', sep='',
          file=file, append=TRUE)
      if(table.env) {
        cap <- paste(caption,
                     '. Factors retained in backwards elimination', sep='')
        if(nr > B)
          cap <- paste(cap, paste(' (first', B, 'resamples).', sep=''))
      }
        else {
          cap <- 'Factors Retained in Backwards Elimination'
          if(nr > B) cap <- c(cap, paste('First', B, 'Resamples'))
          cap <- paste(cap, collapse='\\\\')
          cat(cap, '\n\n', file=file, append=TRUE)
        }
      latex(varin, ..., caption=if(table.env) cap,
            title=paste(title,'retained', sep='-'),
            rowname=NULL, file=file, append=TRUE,
            table.env=table.env, center='none',
            extracolsize=extracolsize)
      if(!table.env) cat('\\end{center}\n', file=file, append=TRUE)
      
      cap <- if(table.env)
        paste(caption,
              '. Frequencies of numbers of factors retained', sep='')
      else {
        cap <- 'Frequencies of Numbers of Factors Retained'
        cat('\\Needspace{1in}\n', sep='',
            file=file, append=append)
        cat('\\begin{center}\\', size, '\n', sep='', file=file, append=TRUE)
        cat(cap, '\n\n', file=file, append=TRUE)
      }
      
      nkept <- apply(kept, 1, sum)
      tkept <- t(as.matrix(table(nkept)))
      latex(tkept, ..., caption=if(table.env) cap,
            title=paste(title, 'freq', sep='-'),
            rowname=NULL, file=file, append=TRUE,
            table.env=table.env, center='none', extracolsize=extracolsize)
      if(!table.env) cat('\\end{center}\n', file=file, append=TRUE)
    }
  }

html.validate <- function(object, digits=4, B=Inf, caption=NULL, ...) {
  chg <- function(x, old, new) {
    names(new) <- old
    tx <- new[x]
    ifelse(is.na(tx), x, tx)
  }
  x <- object
  kept <- attr(x, 'kept'); attr(x, 'kept') <- NULL
  cn <- colnames(x)
  cn <- chg(cn, c('index.orig', 'training', 'test', 'optimism',
                  'index.corrected', 'n'),
            c('Original<br>Sample', 'Training<br>Sample',
              'Test<br>Sample', 'Optimism', 'Corrected<br>Index',
              'Successful<br>Resamples'))
  rn <- rownames(x)
  rn <- chg(rn, c('Dxy','R2','R-square','Emax','D','U','Q','B','g','gp','gr',
                  'rho','pdm'),
            c('<i>D<sub>xy</sub></i>',
              '<i>R<sup>2</sup></i>','<i>R<sup>2</sup></li>',
              '<i>E<sub>max</sub></i>','<i>D</i>','<i>U</i>',
              '<i>Q</i>','<i>B</i>','<i>g</i>','<i>g<sub>p</sub></i>',
              '<i>g<sub>r</sub></i>','<i>&rho;</i>',
                'Mean |Pr(Y&ge;Y<sub>0.5</sub>)-0.5|'))
  
  dimnames(x) <- list(rn, cn)
  cdec <- ifelse(cn == 'Successful\nResamples', 0, digits)
  ## Bug in htmlTable::txtRound for vector digits
  z <- unclass(x)
  for(i in 1 : length(cdec)) z[, i] <- round(z[, i], cdec[i])

R <- as.character(
  htmlTable::htmlTable(z, rowlabel='Index', caption=caption,
                           escape.html=FALSE) )
  
                         
  if(length(kept) && B > 0) {
    varin <- ifelse(kept, htmlSpecial('mediumsmallwhitecircle'), ' ')
    nr <- nrow(varin)
    varin <- varin[1:min(nrow(varin), B),, drop=FALSE]
    cap <- 'Factors Retained in Backwards Elimination'
    if(nr > B) cap <- paste0(cap, '<br>First ', B, ' Resamples')
    R <- c(R, as.character(
                htmlTable::htmlTable(varin, caption=cap, rnames=FALSE,
                             escape.html=FALSE)))

    cap <- 'Frequencies of Numbers of Factors Retained'
    nkept <- apply(kept, 1, sum)
    tkept <- t(as.matrix(table(nkept)))

    R <- c(R, as.character(
               htmlTable::htmlTable(tkept, caption=cap, rnames=FALSE,
                                     escape.html=FALSE) ))
  }
rendHTML(R)
}
